The present invention relates to magneto-optical disk apparatuses, and more particularly to a magneto-optical disk apparatus which operates according to a magnetic field modulation and has a magnetic head loading mechanism.
Laser power modulation, which is employed in earlier types of magneto-optic disk apparatuses, is characterized by a slow data transmission speed during the recording since this modulation system does not have overwrite capability.
Accordingly, a magnetic field modulation is now used as a recording system capable of performing an overwrite operation easily.
A floating magnetic head slider system used in a magnetic disk apparatus of a hard disk has advantages of high-density recording and low power consumption and is proposed as a magnetic head to be used in the magnetic field modulation.
Unlike a magnetic disk apparatus, an interchangeable medium is used in a magneto-optical disk apparatus. Thus, there is a need for a magnetic head loading mechanism whereby the magnetic head is moved away from a disk and set again above the disk after the disk has been changed.
It is a convention in a magneto-optical disk apparatus to control an optical head with respect to light beam focus and with respect to tracking performance. A seek control whereby the entire movable part of the head is moved to a predetermined track is also performed. In order to execute these controls in a high-precision and stable manner, it is required that the movable part of the head be constructed to be light and highly rigid.
The Japanese Laid-Open Patent Applications No.3-19159, No.3-19160 and No.3-104068 propose disk apparatuses having a magnetic head loading mechanism.
In No.3-19159 and No.3-19160, a connecting member of an optical head is connected to a second elastic body. The second elastic body is connected to a first elastic body. A magnetic head is fitted to the end of the first elastic body. In an unloading operation, the first elastic body is thrust upward by a support rod or a vertically-moving rod so that the magnetic head is moved away from the disk. In a loading operation, the support rod or the vertically-moving rod is released so that the magnetic head is located above the disk.
No.3-104068 discloses a construction in which the back end of a load beam (support arm) which has a magnetic head attached to the end thereof is connected to a blade spring. In this construction, in a loading operation, an upper plate is slid on and restrains the blade spring so that the magnetic head is located above the disk.
However, the constructions as described in No.3-19159 and No.3-19160 have a problem in that since the magnetic head is supported by the first and second elastic bodies and is connected to the optical head, the rigidity of the movable part of the head is significantly small. Specifically, the magnetic head slider is maintained in a floating position, with a lift generated by an air flow resulting from the rotation of the disk being in balance with a pressure caused by the deflection of the first elastic body (load beam), and the load beam is supported by the second elastic body. In the event of a variation in the slider orientation or a vibration of the slider, which variation and vibration are caused as result of the acceleration of the head in a seek operation or as a result of an external vibration, an error may occur in a recording signal, or the head may clash against the disk.
While construction as described in No.3-104068 ensures that the rigidity of the movable part of the head is satisfactory, it has the following problems: the movable part of the head is relatively heavy and large; positional precision and stability of the head is relatively unsatisfactory; and power consumption during a seek operation is relatively large.
Another problem common to all of the three constructions described above is that, since the magnetic head loading mechanism is built in the movable part of the head or the frame part (fixed part), the mechanism occupies a relatively large space, with the result that an effort to make the apparatus small and thin so as to fit in small-scale electronic apparatuses is thwarted.